2nd Partition on 5TB RAID 5 Array running W2K3

Go into computer managment & create the partition there. You should be able to create it & format it from there.

I believe that's where I'm trying to create the partition at

R-click "My Computer" -> manage -> Disk Management

Then on disk 0 I have the C: partition and an unallocated 2.6GB space. When I R-click the unallocated space the option New Partition is grayed out.

Err that an unallocated 2.6 TB not GB

Sorry ... I meant to summarize by saying there is no easy way to use the entire space at this point, as you can't "remove" drives from your existing RAID 5.  In either situation, you would be doing a complete backup and restore.

It is not a partitioning problem, it is a LUN/device limit.    I.e, if you have a single physical disk drive, then that is one target device.  If you partition it into C & D, then you still have a single target device, but it is partitioned into 2 LUNs, or volumes or logical devices.

On the RAID you have same thing, you effectively made a 5TB physical disk drive (as seen by the O/S).  By partitioning it, you still have a 5TB device you split into C &D.  That is no good. The 32-bit limit of FFFFFFFFh blocks is the most that can be used with this O/S (which is 2.09 TB when FFFFFFFF hex is multiplied by 512)

You need to create 2 different SCSI IDs with the RAID,  a C disk and a D disk, not a partitioned C drive.  Some controllers will let you partition (at the RAID level) a single RAID set into multiple targets.  

W/o looking up the specs, don't know if this one will, but chances are it will not.  You'll just have to create a single RAID1 with 2 disks, and make that C, and then use the other disks for the D drive

So far only the OS is on there so I'd just start over from scratch. With that in mind I have 6 x 1TB drives I need at least a 500GB W2k3 boot partition, the rest can be a different partition, all in RAID 5. If I start over can I make 1 array with 84 GB from each disk and the rest in a 2nd array or will I have to split it 3 and 3 ending up with about 4TB total to have all of it in RAID 5?

ok I see I can't use part of the a disk its all or nothing so 1 RAID 1 array of 2 disks and 1 RAID 5 of 3 disks

OK I went with the RAID 1 and RAID 5 setup and Googled win2k align partitions and found

http://blog.bennett-scharf.com/2008/03/31/using-diskpart-to-align-a-windows-disk-partition/

and

http://blogs.msdn.com/b/jimmymay/archive/2008/10/14/disk-partition-alignment-for-sql-server-slide-deck.aspx

Is this something that needs to be done during OS install or can it be done after OS install?

On a 2950, I would assume you are using a PERC 5 or 6, which will both support "slicing" - or creating multiple arrays across the same set of disks - if you want to go that route.  When creating the array in CTRL-R, specify the size you want the first array to be, then later you can create an array with the remaining space.

Its a PERC 5/i controller but I've already went with the RAID 1 and RAID 5 arrays

It's better that way, but since I missed the discussion, I thought I'd throw that out there for information's sake.

Personally I do it before when convenient, but you have to be able to boot that system first.  If you have a USB-attached windows disk with the RAID drivers, then do formatting / partitioning on NTFS first.  Then installation will go a little faste

I'll have to do the alignment after I get the OS installed, thanks for all the help going to close that and split the points between the two of you.

Good luck.